A Calgary police officer on trial for assaulting a member of the Hells Angels who'd become abusive and threatening during an arrest testified in his own defence on Wednesday.

Const. Brant Derrick told provincial court Judge Josh Hawkes he believed, based on his training, he was entitled to use the force necessary to get Jason Arkinstall into a police vehicle when he began aggressively resisting the officer.  

Derrick and Sgt. Les Kaminski — president of the Calgary police union — were arresting Arkinstall following a traffic stop in 2008 because they believed he was breaching his release conditions. The officers didn't know at the time that the charge against Arkinstall had been withdrawn by B.C. authorities.

As soon as the officers tried to arrest Arkinstall — who was wearing a Hells Angels T-shirt at the time — he began cursing at them. Derrick said he feared for his safety at the time.

Once out of the truck Arkinstall immediately began resisting being placed in handcuffs, said Derrick.

"He's swearing, 'f--k you, you're f--king dead, my lawyer's going to get you,'" Derrick explained in court.

'Physical control tactic'

Once Arkinstall was cuffed, he was escorted to the back of the police van. Derrick said he had a hand on the back Arkinstall's neck as they walked. 

Once there, Arkinstall began pushing back against the officer, which Derrick said caused him to stumble backward a couple of steps. 

At that point, Derrick said he felt Arkinstall was resisting arrest and believed, based on CPS policy, he was entitled to use the force necessary to gain control over the arrest. 

Derrick said he used a single open-hand palm strike to the back of Arkinstall's head as a "physical control tactic."

He then pushed Arkinstall toward the back of the police van's prisoners' cage. At that point Arkinstall dove into the back of the van, according to Derrick.

"He actually stops his backward resistance and as I push, he propels himself sideways into that vehicle."

Excerpt of 2008 arrest of Jason Arkinstall0:39

Derrick denied shoving the suspect into the van, as the video appeared to show.

"I don't think I could take a 210-pound man and throw him like that," Derrick

The video also shows Derrick slamming the cage door two or three times on Arkinstall's legs, which the officer explained was because the suspect was kicking at the gate. 

Arkinstall was charged following the incident but was acquitted of uttering threats in 2011, in part because the judge did not find Derrick or Kaminski to be credible witnesses. Their accounts of the arrest contradicted the video, which was played by the Hells Angel's lawyer.

Calgary police conducted a review after Arkinstall's trial but determined an investigation was not required, which they've since called a "mistake."

Arkinstall convicted in Spain

The Alberta Serious Incident Response Team (ASIRT) became involved in 2014 but that investigation faced several delays; first investigators had trouble getting the video because Arkinstall's lawyer wouldn't tell them where he got it and then because Arkinstall was arrested overseas.

Arkinstall and Scott Smitna — who was driving during the 2008 traffic stop — were convicted of smuggling 300 kilograms of cocaine in Spain in May 2015, which also complicated the matter.

Instead of serving their four-year, seven-month sentence the pair paid an $8-million fine and were kicked out of the country. They immediately returned to Canada.

Charges against Derrick and Kaminski were laid in January.

Kaminski's assault charge was withdrawn and he faces a trial for perjury stemming from the same incident.